The invention relates to a cassette including an information disc and a housing having main walls disposed parallel to the disc and transverse walls interconnecting the main walls. The walls define an internal receiving space in which the information disc is mounted for rotation, at least one of the walls having an aperture for access of the pick-up to the disc surface inside the housing.
Such a cassette is known, for example, from the Applicant's prior European Patent Application 0,255,185 A1 U.S. application Ser. No. 860,729, herewith incorporated by reference). The relevant cassette has a single shutter which is slidable over the outside of the housing to close apertures formed in the two main walls of the housing for the access of a pick-up. For the remainder the housing is imperforate and comprises two shells which are interconnected permanently or semi-permanently, for example by gluing, ultrasonic welding etc. or by fixing means such as screws, which can be removed with the aid of a tool. The cassette is intended for a so-called DOR disc (Digital Optical Recording), which is permanently accommodated in the internal receiving space of the cassette.
It is not always desirable that information discs are permanently accommodated in cassettes. Some information discs, for example CD-ROM discs (Compact Disc Read Only Memory) are provided with a permanent program by means of a replica method. Such discs, just like normal Compact Discs, need not necessarily be accommodated in a housing because the information recorded on the disc is in principle protected against touching and soiling. However, in the case of professional discs, such as the CD-ROM discs, a protection is frequently desirable because the recorded information may be far more susceptible to read errors and, in addition, the disc may be far more valuable.
Therefore, such professional Compact Discs are sometimes also accommodated in a cassette. In accordance with a non-prepublished proposal, this may be achieved in a manner for a specific type of video disc, as in U.S. Pat. Nos. 4,361,884 and 4,463,850 (herewith incorporated by reference). These known cassettes include a housing basically consisting of a sleeve which is closed by a cross member of a disc holder at a front side. Limbs which engage around the video disc inside the sleeve are connected to the cross member. The cassette with the cross member facing forwards is bodily inserted into a slot in a player, the disc holder being released inside the player. When the sleeve is withdrawn the disc holder with the disc remains inside the player. When the sleeve is re-inserted into the player the disc is re-introduced into the sleeve and the disc holder is latched to the sleeve, after which the cassette can be removed from the player as a closed unit. In cassettes of this type it is not easy, and moreover it is generally not intended, to remove the disc from the cassette and to replace it by another disc. The latching means with which the disc holder is latched to the sleeve are so constructed that they cannot readily be opened by hand from the exterior, not even with the aid of tools.